1. Technical Field
The present invention relates to battery-powered electronic devices that operate and receive power from batteries, battery packs and charger units and determine whether batteries or battery packs are inserted in the battery-powered device.
2. Related Art
Many electronic devices have become portable enabling their users to remain mobile while receiving the benefits of the portable device. These electronic devices generally require batteries or battery cells to supply the required power for operation, and may include digital cameras, camcorders, wireless microphones, laptop computers, cell phones, and power tools. Many of these devices may have a display that indicates the remaining charge of the battery or battery pack associated with the device. Thus, the operator can determine whether the device will perform as required without running out of power at some critical point. If the remaining charge is too low, the operator may plug the device into a power supply, charging the batteries or battery pack while operating the device simultaneously.
Battery packs are available that have at least one, but generally two or more, rechargeable batteries or battery cells. Contrary to the name, battery packs do not have ordinary batteries, but may contain rechargeable cells. Some battery packs are equipped with a monitoring unit by which a variety of the device operating parameters may be monitored, stored, and displayed. The monitoring unit may query and monitor the state of charge, the state of the battery, and/or the status of the charging unit through contacts provided on the battery pack. The status of the battery pack may be communicated to the battery powered device. Such a device is described in U.S. Pat. No. 6,437,536 and is herby incorporated by reference in its entirety. However, this device does not discriminate between ordinary batteries that are individually inserted into the device and the battery packs that might hold the ordinary batteries.
Special battery charging units may connect directly to the battery-powered device and may contain slots for inserting storage batteries or battery packs. Some battery charging units may allow the batteries to be inserted into the special slots in the charging unit when the charging unit is removed from the electronic device. Other battery charging units allow for several battery packs or storage batteries to be inserted and charged simultaneously. Still other battery chargers may simultaneously charge the storage batteries that are inserted into the charging unit as well as charge the storage batteries that are in an electronic device connected to the charger. As previously mentioned, a data exchange also may occur between the charging unit and the electronic device, communicating the state of the battery pack and the status of the charging unit. Other chargers may be configured to serve as a line voltage-device, supplying power to the electronic device while keeping a trickle charge on the fully charged batteries within the electronic device.
These contemporary power supplies exchange information between the battery pack and the charger, and sometimes to the device in which the battery pack is found. This exchange of information may be accomplished with additional lines through the use of different bus systems. In many applications, especially in radio microphones, there are requirements concerning electromagnetic interference of such devices. The bus systems, because of their location within the system, may exhibit or produce interference radiation, posing a problem for many applications. Another problem may involve additional contacts between the battery pack and the device. Openings in the area of the battery shaft have been avoided in order to protect the electronic circuitry against electrostatic discharge. The additional contact points in the housing represent not only an extra cost, but may present problems because of the additional contacts and openings in the battery shaft area.
Various devices and methods have been developed to determine the amount of charge remaining in a battery. For example, a solution is provided in U.S. Pat. No. 6,344,730 A, which is hereby incorporated by reference. This solution is based on the relationship between voltage and the charge in the batteries. However, it has not solved the problem where different types of rechargeable batteries have been incorporated or where the quality of the batteries in use varies. Thus, there is a need for the battery-powered device to determine whether individual batteries or battery cells have been inserted into the battery shaft.